forked from extern/nushell
75 lines
2.2 KiB
Rust
75 lines
2.2 KiB
Rust
use nu_engine::{eval_block, eval_expression};
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use nu_protocol::ast::Call;
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use nu_protocol::engine::{Command, EvaluationContext};
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use nu_protocol::{IntoValueStream, Signature, Span, SyntaxShape, Value};
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pub struct For;
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impl Command for For {
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fn name(&self) -> &str {
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"for"
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}
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fn usage(&self) -> &str {
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"Loop over a range"
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}
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fn signature(&self) -> nu_protocol::Signature {
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Signature::build("for")
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.required(
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"var_name",
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SyntaxShape::Variable,
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"name of the looping variable",
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)
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.required(
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"range",
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SyntaxShape::Keyword(
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b"in".to_vec(),
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Box::new(SyntaxShape::List(Box::new(SyntaxShape::Int))),
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),
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"range of the loop",
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)
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.required("block", SyntaxShape::Block, "the block to run")
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}
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fn run(
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&self,
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context: &EvaluationContext,
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call: &Call,
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input: Value,
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) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
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let var_id = call.positional[0]
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.as_var()
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.expect("internal error: missing variable");
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let keyword_expr = call.positional[1]
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.as_keyword()
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.expect("internal error: missing keyword");
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let values = eval_expression(context, keyword_expr)?;
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let block = call.positional[2]
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.as_block()
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.expect("internal error: expected block");
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let context = context.clone();
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match values {
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Value::List { val, .. } => Ok(Value::List {
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val: val
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.map(move |x| {
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let engine_state = context.engine_state.borrow();
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let block = engine_state.get_block(block);
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let state = context.enter_scope();
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state.add_var(var_id, x.clone());
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//FIXME: DON'T UNWRAP
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eval_block(&state, block, input.clone()).unwrap()
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})
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.into_value_stream(),
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span: call.head,
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}),
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_ => Ok(Value::nothing()),
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}
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}
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}
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